THE WHITE PINE BLISTER DISEASE 



69 



are encountered who, rather than sacrifice a few dollars, 

 or in some cases less than a dollar, will object to removal 

 of their bush or tree and thus endanger hundreds and' even 

 thousands of dollars' worth of trees or bushes in their 

 locality, besides giving the disease a chance to become so 



to the white man, relatively mild disease. In the same 

 way the smallpox destroyed entire tribes. 



The same thing that happened to the Indians from 

 newly introduced diseases is already happening to one of 

 our broad-leaved trees. The American chestnut, lacking 



Photograph by J. Franklin Collins. 



TWO MORE VICTIMS 

 Both these native white pines in Maine have been killed by the pine blister 

 disease and all the trees in the background are infected. 



well established that it never can be eradicated. The 

 Federal Government has put a stop to our receiving any 

 more young diseased white pines from abroad. It 

 remains for us to get rid of what we have. Either the 

 white pines or the currants and gooseberries must go in 

 many localities if this disease is to be stopped in its spread. 

 It is a well proven fact, known to all students of para- 

 sitic diseases, either of plants or animals, that constant 

 association for many centuries with a parasitic disease 

 develops some degree of resistance in the host plant or 

 animal. This results from the total destruction of those 

 individuals which fail to develop resistance, thus leaving 

 a residue of partially resistant ones. In the early days of 

 exploration of North America the measles was introduced 

 among the North American Indians from the Old World. 

 The Indians, who had not the slightest degree of resistance 



Photograph by S. B. Detwiler. 



175 INFECTIONS ON THIS PINE 

 This tree at Ipswich, Massachusetts, was imported from France in 1902. It 

 was removed from the plantation in 1916 at which time there were 175 pine 

 blister disease infections on it. Some of them are shown, being marked by 

 white tags. 



the ability to resist a new chestnut parasite imported 

 from China, is now well on the road to extermination. 



In those places (in this country) where this European 

 pine rust has worked longest undisturbed, it is 

 doing with our non-resistant white pine just what the 

 paleface disease did to the Indians and the foreign 

 chestnut disease is now doing to our chestnuts. It has 

 shown itself positively capable of destroying our white 

 pine. The eastern white pine is not the only American 

 white pine that is threatened by this insidious danger. 

 There are seven other pines of the Rocky Mountain 

 and Pacific Coast regions that will surely be attacked if 

 this disease is not fought to a standstill where it now is. 

 All of these are new to the disease and are likely to go 

 the way of the Indian with the smallpox and the chestnut 

 with the bark disease, if the white pine blister disease 

 once reaches them. 



to the new disease, were destroyed in thousands, by this, 



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WHAT SHALL WE DO ABOUT THE PINE BLISTER DISEASE? 

 By S. B. Detwiler, U. S. Forest Inspector 



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DEVELOPMENTS in the pine blister disease situa- 

 tion during the past year have crystallized senti- 

 ment among those interested in forestry and fa- 

 miliar with the facts into desire for immediate and 

 concerted action. A few conservatives have taken the 

 attitude that it is useless to attempt the control of any 

 forest tree disease in this country because it has never 

 been done. The general opinion among foresters and 

 plant pathologists is that the white pine is too valuable to 

 lose and that vigorous efforts should be made to fight the 



pine blister, since there is no longer room to doubt 

 the ability of this disease to completely kill all white 

 pines growing in proximity to currant and gooseberry 

 bushes Although it is not proved by practical exper- 

 ience on a large scale that the disease can be completely 

 controlled by the destruction of diseased pines and the 

 elimination of all currant and gooseberry plants within 

 areas of general disease, this plan has proved to be 

 effective in checking the spread of the fungus from in- 

 fected plantations. 



